Miscellaneous pull requests just merged for 0.8

Some small features that might make your life easier just got merged in:

* playbooks can import playbooks in other (different) directories and
then be able to import tasks relative to them

* ansible config file can also go in '.ansible.cfg' in your current
working directory in addition to ~/.ansible.cfg and
/etc/ansible/ansible.cfg

* $group and $group_names are now accessible in with_items

* you can now pass a list of host patterns to the inventory API again
versus having to colon seperate them (regression from 0.6 I think)